I have 2 seemingly identical KDE4 entries in KDM, and from looking around my FS I believe they are
Running equery b on the files, reveals they both belong to kde-base/kdebase-startkde-4.7.0. Further inspection with diff reveals that the files are identical in content.
I think this issue was already occurring under KDE 4.6, but I have only verified it after installing 4.7.
Surely one of the files is redundant? (My guess would be the /usr/share/apps/kdm/xsessions copy)
I was lying, the files are provided by different packages :S
The kdm file should not be present?
luca@optipad ~ $ equery b /usr/share/xsessions/KDE-4.desktop
* Searching for /usr/share/xsessions/KDE-4.desktop ...
luca@optipad ~ $ equery b /usr/share/apps/kdm/sessions/kde-plasma.desktop
* Searching for /usr/share/apps/kdm/sessions/kde-plasma.desktop ...
Problem is known and identified (this is the side effect of fixing a different bug), I just dont know yet how to resolve it best...
Fixed in 4.7.2-r1, thanks.